Direct antiglobulin test; Indirect antiglobulin test
No clumping of cells (agglutination), indicating that there are no antibodies to red blood cells, is normal.
Normal value ranges may vary slightly among laboratories. Talk to your doctor about the meaning of your specific test results.
An abnormal (positive) direct Coombs' test means you have antibodies that act against your red blood cells. This may be due to:
The test is also abnormal in some people without any clear cause, especially among the elderly. Up to 3% of people who are in the hospital without a known blood disorder will have an abnormal direct Coombs' test.
An abnormal (positive) indirect Coombs' test means you have antibodies that will act against red blood cells your body views as foreign. This may suggest:
Powers A, Silberstein LE. Autoimmune hemolytic anemia. In: Hoffman R, Benz EJ Jr., Shattil SS, et al., eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Churchill Livingston Elsevier; 2008: chap 47.
Schrier SL, Price EA. Extrinsic nonimmune hemolytic anemias. In: Hoffman R, Benz EJ Jr., Shattil SS, et al., eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Churchill Livingston Elsevier; 2008: chap 48.
Schwartz RS. Autoimmune and intravascular hemolytic anemias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 164.
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